Diagnosed with Bell's Palsy. Prescribed with Prednisone and Valtrex. Is it safe to give diphenhydramine during night?

My 17 year daughter was just diagnosed with Bell's Palsy. She has been prescribed 10mg Prednisone, and Valtrex, which she took this evening at 8pm. It is now almost midnight and she is having a hard time sleeping-is it safe to give her a nighttime sleep aid such as diphenhydramine?

Brief Answer:
Diphenhydramine can be given. Zolpidem preferred
Detailed Answer:
Hi Mrs. XXXXXXX
Thanks for posting your query on XXXXXXX Forum.
Firstly, you can give diphenhydramine as it does not interact with the medications your daughter is already taking. However, Zolpidem 5mg would be a better proposition for sleep.
Further, if I had been your daughter's treating doctor, I would have followed the standard practice of prescribing Prednisone with starting dose of 1mg/kg body weight. For example, if your daughter's weight is say, 50kg, the initial dose of Prednisone should have been 50mg/day, which is then reduced by 5mg everyday. An initial high dose hastens recovery.
It is is my personal opinion. You may however, re-consult your daughter's treating doctor, who may like to review his prescription.
Hope you find my response helpful, informative and enlightening. I would be happy to answer further clarifications, if any.
Fond regards,
Dr. Rakesh Karanwal